This invention relates to electronic musical instruments, and more particularly to pedal control circuits for an electronic piano. Systems are known from Peterson U.S. Pat. Nos. 3,444,306 and 3,602,628 for producing sounds from electronically generated tone signals that substantially duplicate the sounds of a conventional piano. The system described in U.S. Pat. No. 3,602,628 includes a continuously oscillating tone gnerator, and gating circuits which deliver signals from the tone generator to an output system with a peak intensity proportional to the velocity with which the playing keys are struck. The system also includes damper circuits which, in conjunction with a sustaining pedal, produces an action analogous to that of the sustaining pedal in a conventional piano.
Conventional pianos, at least the more expensive ones, also include a sostenuto pedal which when operated sustains any notes corresponding to keys that are depressed at the time the sostenuto pedal is depressed, but does not sustain any notes that are played after operation and during the period the sostenuto pedal remains depressed. It is desirable to provide a comparable action, at reasonable cost, in an electronic piano.
Conventional pianos also have a volume pedal, a two-position pedal operative to provide a normal volume in its normal unoperated position and a softer volume in the other position, the level of the tone in either case being determined at the moment that the piano string is struck by a hammer. It is desirable to provide a comparable volume control in electronic pianos, especially in the sense that the level of the tone is determined only at the moment of strike of a key. Indeed, it is desirable to improve upon the volume control of a conventional piano by providing more than two distinct control levels and a wider dynamic range than that of a conventional piano, to permit loud passages to be played with less physical effort and soft passages to be played with more precision.
Accordingly, the object of the present invention is to provide improved pedal control circuits for an electronic piano which operate in conjunction with the associated tone generating system to provide actions analogous to that of a sustaining pedal, of a sostenuto pedal, and of a volume pedal in a conventional piano.